Eighty individuals with MAP will be randomly assigned into two treatment groups, i.e. treatment with quetiapine and haloperidol. The quetiapine group will receive quetiapine at least 100 mg per day and the haloperidol group will receive haloperidol at least 2 mg per day orally once a day for four weeks. The doses will be increased every 5 days until no psychotic symptom is observed from the Positive and Negative Syndrome Scale. Common antipsychotic adverse events will be checked and documented daily.